/*
** $Id: ltablib.c,v 1.65 2013/03/07 18:17:24 roberto Exp $
** Library for Table Manipulation
** See Copyright Notice in lua.h
*/


#include <stddef.h>

#define ltablib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


#define aux_getn(L,n)	(luaL_checktype(L, n, LUA_TTABLE), luaL_len(L, n))



#if defined(LUA_COMPAT_MAXN)
static int maxn (lua_State *L) {
	lua_Number max = 0;
	luaL_checktype(L, 1, LUA_TTABLE);
	lua_pushnil(L);  /* first key */
	while (lua_next(L, 1)) {
		lua_pop(L, 1);  /* remove value */
		if (lua_type(L, -1) == LUA_TNUMBER) {
			lua_Number v = lua_tonumber(L, -1);
			if (v > max) max = v;
		}
	}
	lua_pushnumber(L, max);
	return 1;
}
#endif


static int tinsert (lua_State *L) {
	int e = aux_getn(L, 1) + 1;  /* first empty element */
	int pos;  /* where to insert new element */
	switch (lua_gettop(L)) {
	case 2: {  /* called with only 2 arguments */
		pos = e;  /* insert new element at the end */
		break;
			}
	case 3: {
		int i;
		pos = luaL_checkint(L, 2);  /* 2nd argument is the position */
		luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds");
		for (i = e; i > pos; i--) {  /* move up elements */
			lua_rawgeti(L, 1, i-1);
			lua_rawseti(L, 1, i);  /* t[i] = t[i-1] */
		}
		break;
			}
	default: {
		return luaL_error(L, "wrong number of arguments to " LUA_QL("insert"));
			 }
	}
	lua_rawseti(L, 1, pos);  /* t[pos] = v */
	return 0;
}


static int tremove (lua_State *L) {
	int size = aux_getn(L, 1);
	int pos = luaL_optint(L, 2, size);
	if (pos != size)  /* validate 'pos' if given */
		luaL_argcheck(L, 1 <= pos && pos <= size + 1, 1, "position out of bounds");
	lua_rawgeti(L, 1, pos);  /* result = t[pos] */
	for ( ; pos < size; pos++) {
		lua_rawgeti(L, 1, pos+1);
		lua_rawseti(L, 1, pos);  /* t[pos] = t[pos+1] */
	}
	lua_pushnil(L);
	lua_rawseti(L, 1, pos);  /* t[pos] = nil */
	return 1;
}


static void addfield (lua_State *L, luaL_Buffer *b, int i) {
	lua_rawgeti(L, 1, i);
	if (!lua_isstring(L, -1))
		luaL_error(L, "invalid value (%s) at index %d in table for "
		LUA_QL("concat"), luaL_typename(L, -1), i);
	luaL_addvalue(b);
}


static int tconcat (lua_State *L) {
	luaL_Buffer b;
	size_t lsep;
	int i, last;
	const char *sep = luaL_optlstring(L, 2, "", &lsep);
	luaL_checktype(L, 1, LUA_TTABLE);
	i = luaL_optint(L, 3, 1);
	last = luaL_opt(L, luaL_checkint, 4, luaL_len(L, 1));
	luaL_buffinit(L, &b);
	for (; i < last; i++) {
		addfield(L, &b, i);
		luaL_addlstring(&b, sep, lsep);
	}
	if (i == last)  /* add last value (if interval was not empty) */
		addfield(L, &b, i);
	luaL_pushresult(&b);
	return 1;
}


/*
** {======================================================
** Pack/unpack
** =======================================================
*/

static int pack (lua_State *L) {
	int n = lua_gettop(L);  /* number of elements to pack */
	lua_createtable(L, n, 1);  /* create result table */
	lua_pushinteger(L, n);
	lua_setfield(L, -2, "n");  /* t.n = number of elements */
	if (n > 0) {  /* at least one element? */
		int i;
		lua_pushvalue(L, 1);
		lua_rawseti(L, -2, 1);  /* insert first element */
		lua_replace(L, 1);  /* move table into index 1 */
		for (i = n; i >= 2; i--)  /* assign other elements */
			lua_rawseti(L, 1, i);
	}
	return 1;  /* return table */
}


static int unpack (lua_State *L) {
	int i, e, n;
	luaL_checktype(L, 1, LUA_TTABLE);
	i = luaL_optint(L, 2, 1);
	e = luaL_opt(L, luaL_checkint, 3, luaL_len(L, 1));
	if (i > e) return 0;  /* empty range */
	n = e - i + 1;  /* number of elements */
	if (n <= 0 || !lua_checkstack(L, n))  /* n <= 0 means arith. overflow */
		return luaL_error(L, "too many results to unpack");
	lua_rawgeti(L, 1, i);  /* push arg[i] (avoiding overflow problems) */
	while (i++ < e)  /* push arg[i + 1...e] */
		lua_rawgeti(L, 1, i);
	return n;
}

/* }====================================================== */



/*
** {======================================================
** Quicksort
** (based on `Algorithms in MODULA-3', Robert Sedgewick;
**  Addison-Wesley, 1993.)
** =======================================================
*/


static void set2 (lua_State *L, int i, int j) {
	lua_rawseti(L, 1, i);
	lua_rawseti(L, 1, j);
}

static int sort_comp (lua_State *L, int a, int b) {
	if (!lua_isnil(L, 2)) {  /* function? */
		int res;
		lua_pushvalue(L, 2);
		lua_pushvalue(L, a-1);  /* -1 to compensate function */
		lua_pushvalue(L, b-2);  /* -2 to compensate function and `a' */
		lua_call(L, 2, 1);
		res = lua_toboolean(L, -1);
		lua_pop(L, 1);
		return res;
	}
	else  /* a < b? */
		return lua_compare(L, a, b, LUA_OPLT);
}

static void auxsort (lua_State *L, int l, int u) {
	while (l < u) {  /* for tail recursion */
		int i, j;
		/* sort elements a[l], a[(l+u)/2] and a[u] */
		lua_rawgeti(L, 1, l);
		lua_rawgeti(L, 1, u);
		if (sort_comp(L, -1, -2))  /* a[u] < a[l]? */
			set2(L, l, u);  /* swap a[l] - a[u] */
		else
			lua_pop(L, 2);
		if (u-l == 1) break;  /* only 2 elements */
		i = (l+u)/2;
		lua_rawgeti(L, 1, i);
		lua_rawgeti(L, 1, l);
		if (sort_comp(L, -2, -1))  /* a[i]<a[l]? */
			set2(L, i, l);
		else {
			lua_pop(L, 1);  /* remove a[l] */
			lua_rawgeti(L, 1, u);
			if (sort_comp(L, -1, -2))  /* a[u]<a[i]? */
				set2(L, i, u);
			else
				lua_pop(L, 2);
		}
		if (u-l == 2) break;  /* only 3 elements */
		lua_rawgeti(L, 1, i);  /* Pivot */
		lua_pushvalue(L, -1);
		lua_rawgeti(L, 1, u-1);
		set2(L, i, u-1);
		/* a[l] <= P == a[u-1] <= a[u], only need to sort from l+1 to u-2 */
		i = l; j = u-1;
		for (;;) {  /* invariant: a[l..i] <= P <= a[j..u] */
			/* repeat ++i until a[i] >= P */
			while (lua_rawgeti(L, 1, ++i), sort_comp(L, -1, -2)) {
				if (i>=u) luaL_error(L, "invalid order function for sorting");
				lua_pop(L, 1);  /* remove a[i] */
			}
			/* repeat --j until a[j] <= P */
			while (lua_rawgeti(L, 1, --j), sort_comp(L, -3, -1)) {
				if (j<=l) luaL_error(L, "invalid order function for sorting");
				lua_pop(L, 1);  /* remove a[j] */
			}
			if (j<i) {
				lua_pop(L, 3);  /* pop pivot, a[i], a[j] */
				break;
			}
			set2(L, i, j);
		}
		lua_rawgeti(L, 1, u-1);
		lua_rawgeti(L, 1, i);
		set2(L, u-1, i);  /* swap pivot (a[u-1]) with a[i] */
		/* a[l..i-1] <= a[i] == P <= a[i+1..u] */
		/* adjust so that smaller half is in [j..i] and larger one in [l..u] */
		if (i-l < u-i) {
			j=l; i=i-1; l=i+2;
		}
		else {
			j=i+1; i=u; u=j-2;
		}
		auxsort(L, j, i);  /* call recursively the smaller one */
	}  /* repeat the routine for the larger one */
}

static int sort (lua_State *L) {
	int n = aux_getn(L, 1);
	luaL_checkstack(L, 40, "");  /* assume array is smaller than 2^40 */
	if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */
		luaL_checktype(L, 2, LUA_TFUNCTION);
	lua_settop(L, 2);  /* make sure there is two arguments */
	auxsort(L, 1, n);
	return 0;
}

/* }====================================================== */


static const luaL_Reg tab_funcs[] = {
	{"concat", tconcat},
#if defined(LUA_COMPAT_MAXN)
	{"maxn", maxn},
#endif
	{"insert", tinsert},
	{"pack", pack},
	{"unpack", unpack},
	{"remove", tremove},
	{"sort", sort},
	{NULL, NULL}
};


LUAMOD_API int luaopen_table (lua_State *L) {
	luaL_newlib(L, tab_funcs);
#if defined(LUA_COMPAT_UNPACK)
	/* _G.unpack = table.unpack */
	lua_getfield(L, -1, "unpack");
	lua_setglobal(L, "unpack");
#endif
	return 1;
}

